Flotation agent



Patente June 29, 1926.

ALBERT L. KLEES, OF NEW YORK, N. Y., ASSIGNOR T0 COMBUSTION UTILITIES COR- PORATION, OF NEW YORK, Y., A CORPORATION OF MAINE.-

FLOTATION AGENT.

No Drawing. Application filed June 7,

This invention relates to a flotation agent, which may be used for effecting concentration of metalliferous ores.

Several well known methods are in general use for concentrating ores, e. g., for increasing the precentage of metal-bearing mineral in the ore by the elimination of a portion of the gangue. In the widely used froth-flotation method the ore is first pulverized and then thoroughly mixed with a large volume of water to form a pulp. This pulp is run through a flotation machine in which by some convenient means there is produced a froth compound of gas or air bubbles and particles of the ore. A small quantity of a flotation agent, usually an oil, is introduced into the flotation machine while the pulp is being formed to produce a sufficiently voluminous and stable froth, and to enhance the selective action of the gas. The flotation oil, if properly chosen, coats or wets the particles of metallic lustre in preference to the particles of gangue. This oily film promotes the adherence of the particles to'the surface of the gas bubble,and;thus results in the selective action whereby the bubbles collector concentrate the mineral-bearing particles on their surface. The froth formed by these bubbles can be readily separated from the large volume of water in which the gangue remains suspended, and this froth on proper treatment such as settling, etc., yields the concentrate.

A wide variety of flotation agents have been used since it has been found that different ores require'various kinds and quantities of such agents. The most widely used flotation agents for copper ores are coal tars, coal-tar creosotes, cresylic acid and kerosene acid sludges,-other oils such as pine oil, etc., being frequently used in small quantities to increase frothing. Sulfuric acid is also used in large quantities as a supplementary agent to obtain a condition of acidity, which is frequently desirable. For lead and lead silver ores hardwood creosote is employed in greatest quantity, followed by coal tars, crude petroleum and pine oils.

Two distinct properties are required of a flotation oil to obtain the desired results. First, the oil must stabilize the froth formed from the Water, the gas and the solids of the pulp; second, it must selectively wet the metallic particles present in the pulp solids. To possess good frothing properties the oil sity for the same boiling point.

1924:. Serial No. 718,674.

' properties the oil must be more readily ab-' sorbed on the surface of the metallic particles than on-that of the gangue particles. No oils will perform both of these functions equally satisfactorily with all ores and in all processes, and hence no flotation agent can be regarded as universally applicable.

The primary object of the present invention is to provide a flotation agent which is comparatively inexpensive, and by means of which a high grade concentration of many metal-bearing minerals can be satisfactorily recovered.

Another object of the invention is to provide a flotation agent the component parts of which can be readily varied to make it more effective for treating by different methods.

With these and other objects in view, the invention consists in the new flotation agents hereinafter described and particularly de-V fined in the claims.

The flotation agent or composition forming the subject-matter of the present invention may be described as an oil containing one or more of three typical groups of compounds which are respectively acidic, basic, and neutral in their properties. The acidic group is composed of alkali-soluble organic hydroxy compounds or tar-acids, of which at least fifty percent boil above 220 C. These acidic compounds are analogous to the higher homologues of phenol which occur in very small quantities in ordinary coke-oven tar, but differ from them by having a larger con tent of hydrogen or more alkyl side chains,

particular ores which give them a higher molecular weight,

a lower refractive index, and a lower den- The basic group is composed of hetero-cyclic unsaturated nitrogen bases, soluble in dilute acid. These basic compounds are analogous to the pyridine-quinoline-acridine series of ordinary coke-oven tar, but differ from them by having a larger content of hydrogen or more alkyl side chains, which give them a higher molecular weight, a lower refractive index, and a lower density for thesame boiling point. The neutral group is composed chiefly of cyclic unsaturated hydrocarbons, insoluble in alkali and dilute acid. They are genetically related to the benzene-naphthalene series of compounds of coke-oven tar,

' tent of hydrogen or more alkyl side chains,

bons and the aromatic hydrocarbons which give them a higher molecular weight,

lower refractive index, and a lower density for the same boiling point. The difference between these cyclic unsaturated hydrocarresent in ordinary coke-oven tar is shown by the fact that the unsaturated compounds decolorize dilute solutions of potassium permanganate or bromine; whereas benzene, naphthalene and their homologues do not.

In its mose widely applicable form the oil forming the subject-matter of this invention consists of a mixture containing fifteen to forty-five per cent of the above described acidic compounds; one to six per cent of the above described basic compounds, and the balance ofthe above described neutral compounds. However, the invention is not limited to these specific mixtures in these proportions, or containing all three of these com onent groups.

T e veral groups of compounds, a mix- .ture 0 -which in proper proportions comprisesthe' invention, can be prepared from the primary or only partially decomposed primary tar obtained by .dist-illingcoal or other bituminous material under mild conditions of carbonization; such, for example, as those described in the United States patent to Henry L. Doherty, No. 1,426,159, granted August 15, 1922, orin the co ending application of Henry 0. Loebell, erial No. 640,828, filed May 23,1923, ventitled Manufacture of water gas, but which conditions are quite different from those which give rise to coke-oven tar, the origin of many ordinary flotation oils. In either'of the processes described in the .above appli-- .cation or patent, coal or other bituminous material is passed in a descending column throu h a shaft furnace and during itspassage t rough one part of thefurnace is :progress'ively carbonized by a rising current of ot-gases. The coal is gradually heated'to' higher temperatures, and its volatile con stituents are carried away by the heating gases without being exposed to temperatures much in excess of those requiredfor their liberation. As a result of these mild con ditions of carbonization the tar condensed from this gas consists of the rimary or only partially decomposed liquid distillateof' the coal and is clearly distinguishable both-in its physical and chemical properties from ordinary coke-oven tar.

This rimarytar has a lower density and lower ree carbon content and is radically different from coke-oven tar in its chemical composition. Thezprimary tar and its various distillates commonly contain ten to fift percent of relatively high boiling taraci s; fifty to ninety percent of non-aromatic hydrocarbons, more than one-half of which areunsat'urated; and one to three percent of nitrogen bases. These tar-acids tain their unsaturatedderivatives with ad ditional hydrogen and alkyl groups attached to their nuclei.

-The primary tar-acids can be isolated by extraction of the tar or its distillates with dilute caustic soda and acidification of the alkaline solution thus formed. The nitrogen bases can be isolated from the oil remaining after this tar-acid extraction by treating it with dilute mineral acid, a solution thus being obtained from which they can be liberated. The residual neutral oil remaining after extraction of the tar-acids and the nitrogen bases constitutes the hydrocarbons of this primary tar. These compounds are characterized by the resence in excess (one-halfto four-fifths o the total) of cyclic unsaturated hydrocarbons which are genetically related to the benzenenaphthalene series of compounds but have a larger content of hydrogen or more alkyl groups.

Theneutral oil which is thus obtained .from primaryor only'partially decomposed primary tar, and which contains such cyclic unsaturated non-aromatic hydrocarbons, has proved in the case of many ores to possess the properties 'of selecting the mineral-bearing metal, i. e., of coating it with an oily film in preference to so coating the gangue. The basic oilcontaining the nitrogen bases also possesses this selective action to a high degree, but differs from the neutral oil in the ores with which it is most effective. It is believed that the superiority of these basic and neutral oils as selective agents can'be ex lained by the presence of unsaturated lin ages in their molecules, b means of which there is promoted a diger sorption at the surfaces of the mineral and gangue. Under certain conditions the cyclic unsaturated hydrocarbon oils have a sufficient froth-forming capacity, but the more soluble basic compounds have been found to possess this property to a much greater extent. Hence these neutral and basic oils can be used separately for flotation of certain kinds of ores, but when used together theyusually give moresatisfactory results.

In cases where the cyclic unsaturated oils and/or the nitrogen bases do not produce a satisfactory froth it has been found that entialad-- the addition to these oils of varying amounts of the high-boiling phenol-like compounds or tar-acids which are present in the primary tar oils greatly increases the frothing properties of theresultant oil. \Vhen a flotation oil comprising a mixture of cyclic unsaturated hydrocarbons and/or heterocyclic unsaturated nitrogen bases together with such hi h boiling phenol-like compounds is ad ed to a pulp of pulverized ore and water, the taracids are distributed betweenthe water and the oil. The comparatively insoluble neutral oil acts as a reservoir for the more solubletar-acids and nitrogen bases, and reduces the dimunition of their frothing power by dilution. Thus it has been found that by properly blending a mixture of cyclic unsaturated hydrocarbons, hetero-cyclic nitrogen bases, and phenol-like compounds, all of which possess some frothing power but which differ in their selectivity, i. e., oiling or collecting power, flotation oils can be prepared by means of which a wide variety of ores can be effectively concentrated.

It has also been found that the particular mixture of high-boiling phenol-like compounds which is present in primary tar oils of the class described is a considerably more effective frothing agent than the mixture of low-boiling and slightly more soluble phenols found in ordinary coke-oven tar.

Moreover, this mixture also possesses selective properties to a degree such as to make its use alone feasible in concentrating many ores, without the addition of neutral oils or other agents excessively selective in their action. lit is possible to add to this wide range of tar-acids occurring naturally in tar a fraction of the lower-boiling members of the series which are more soluble in water, and thus to modify the selective and frothing properties of the resultant oil.

The differences in constitution between a coke-oven tar and a primary tar such as is produced by the Doherty or Loebell processes have been discussed, and it is these differences which are believed to be responsible for the pronounced improvements thus made in the technology of ore concentration. A cheaper flotation agent is made possible because these primary tars contain naturally a far higher percentage of the de-.

sirable phenol-like compounds than do cokeoven tars. 'Morever, it has been found that the selective properties and frothing ability of oil from thissource are superior to those of flotation agents available at present. The

'distillates of such primary tar contain these tar acids, basesy-and neutral oils naturally inabout the proportions which are effective in promoting flotation under th conditions most often encountered. Moreover, almost any other combination can be prepared at little expense from these acidic, baslc and neutral oil components. llt is apparent that polycyclic phenolic compounds.

neutral components to meet special conditions, and since all of'the various mixtures prepared from these primary tar oils have a much lower viscosity than the correspond ing fractions from coke-oven tar they can be more readily and completely disseminated through the pulp and hence are far more efficient flotation agents.

Although the invention has been described with reference to the high boiling tar-acids W or phenol-like compounds and the cyclic unsaturated hydrocarbons and hetero-cyclic nitrogen bases which are recovered from a primary or only partially decomposed primary tar such as that produced by the Doherty or Loebell processes, it is not intended to limit the invention to the use of specific tar produced in these two processes or to its distillates or acidic, basic, and

235: any hydrogenated and alkylated derivatives of the higher homologues of phenol of which at least fifty per cent boil above 220 6.; that any hetero cyclic unsaturated nitrogen bases which are hydrogenated and alkylated derivatives of the pyridine-quinoline-acridine series; and that any cyclic unsatu-' rated hydrocarbons which are the similar derivatives of the benzene-naphthalene-anthracene series, can be used and combined in making flotation agents having similar properties;

The term phenol-like compounds has been chosen to define the mixture of taracids or alkali-soluble organic hydroXy-com 300 pounds which are present in the above described primary or only partially decomposed primary tar. It is to be understood, therefore, that the term phenol-like compounds is used in the claims as a generic term to cover compounds analogous to or prototypes of ordinary phenols, such as the hydrogenated or alkylated derivatives of the homologues of phenol, naphthol and The preferred form of the invention hav ing been thus described, what is claimed as new is: y

1. A flotation agent containing cyclic unsaturated hydrocarbons" which are the hydrogenated and alkylated derivatives of aromatic hydrocarbons.

2. A flotation agent containing a mixture of cyclic unsaturated derivatives of aromatic hydrocarbons together with phenol-like compounds of which at least fifty per cent by volume boil above 220 C.

3. A flotation agent containing a mixture of cyclic unsaturated derivatives of aromatic hydrocarbons and their homologues together unsaturated nitrogen least fifty. per cent by volume boil abov. forty-five per cent by volume 'of higl boil- 220 C. ing phenol-like compounds, one to super 5. A flotation agent containing high boilcent by volume of hetero-cyclic unsaturated ing phenol-like compounds, hetero-cyclic unnitrogen-bases, and more than twenty-five 5 saturated nitrogen bases and cyclic ,uhsatuper cent by volume of cyclic unsaturated rated derivatives of the aromatic hydrohydrocarbons."

carbons.

6. A flotation agent containingfiftee-n to ALBERT L.

In testimony wbereof I afiix my signature; 

